$ { \left[\begin{array}{rr}{0} & {0} \\ {-2} & {4} \\ {1} & {-1}\end{array}\right]+\left[\begin{array}{rr}{2} & {4} \\ {4} & {3} \\ {2} & {-1}\end{array}\right] = {?} } $
Answer: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{0}+{2} & {0}+{4} \\ {-2}+{4} & {4}+{3} \\ {1}+{2} & {-1}+{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{2} & {4} \\ {2} & {7} \\ {3} & {-2}\end{array}\right]}$